their baleen—plates in the mouth that filter prey from water—can grow 15 feet long.

But one of their most eye-opening attributes is their longevity. Chemical analysis on samples from whale eyeballs the size of billiard balls revealed ages up to an estimated 211 years. Accounting for a margin of error of about 16 percent, the oldest bowhead studied could have been up to 245 years old—no other mammal is known to have lived as long.

More than 13,000 bowheads swim off Alaska’s coast, but threats are growing. Oil and gas exploration will impact bowhead habitat and increases the stresses whales face.

“We know they react to the noise of activity related to oil drilling at distances of more than 12 miles,” explains bowhead researcher Craig George. Offshore oil and gas exploration means not only more underwater clanging, humming and pounding, but also increased vessel traffic.

As sea ice retreats, commercial shipping lanes will likely bring additional traffic. “Only a few bowheads show propeller injuries at present,” says George, “but as activities pick up, we should expect more whales to get struck by ships.”